With current trends in suburban development, infrastructure limitations generally result in increasing congestion along feeder routes due to the increasing number of vehicles requiring access to urban areas. Additionally, high density urban housing developments create further congestion and limit access and visibility while driving. This often leaves motorists with limited notice of potential hazards, and fewer options for route adjustment to avoid congested areas. For most road users this poses little more than an inconvenience, easily remedied by lowering their rate of speed, increasing travel time and keeping in tight control of their vehicle.
Emergency vehicles, however, must avoid congested routes or provide appropriate notification to traffic users to clear the desired route for passage of the emergency vehicle. The inherent urgency of emergency vehicle travel necessitates effective notification to other traffic to clear the route as quickly as possible. It has become increasingly difficult to timely notify and navigate congested traffic through urban and suburban areas. It is also generally desirable for emergency vehicles to be able to travel at speeds greater than those permitted for other vehicles. Emergency vehicles travelling at high speeds through congested areas pose a risk to all users of the roadway, as well as to individuals seeking emergency assistance.
Common methods of warning motorists of an approaching emergency vehicle include visual and audible warning devices (lights and sirens of various patterns). Most provinces or states have laws requiring motorists to pull over when such warning mechanisms are near, allowing emergency vehicles the right of way while reducing opportunity for collision.
Warning lights and sirens, however, have limitations. While the majority of drivers are aware of appropriate action to take when an emergency vehicle is approaching (for example, pulling over to the right side of the road), drivers are often startled by lights and sirens approaching from behind, and are also often confused as to the direction of the approaching emergency vehicle. Accordingly, there may be limited opportunity for the driver to manoeuver out of the path of the emergency vehicle. This causes erratic motorist response, and confusion for all parties. It is therefore common for emergency vehicles to be seen weaving in and out of such erratic/stalled traffic.
Thus, drivers of emergency vehicles typically must proceed more slowly than desirable, increasing their response time.
U.S. Pat. No. 5,307,060 to Prevulsky, describes a vehicle to vehicle emergency communication system. Emergency vehicles are equipped with transceivers for communication with other emergency vehicles, and for sending alerts to non-emergency vehicles. Non-emergency vehicles are equipped with a vehicle alert receiver to receive permit notification of an approaching emergency vehicle and its type.
Similarly, U.S. Pat. No. 6,529,831 to Smith, describes an in-vehicle notification and navigation system to allow a driver to navigate away from the path of an second (presumably an emergency) vehicle.
Beinke, in U.S. Pat. No. 6,404,351, teaches a system for installation in emergency vehicles. The system not only notifies other vehicles of approaching emergency vehicles, but also has the ability to change traffic lights in a further effort to clear the roadways for emergency traffic. Non-emergency vehicles receive in-car alerts via an installed directional display and speaker.
U.S. Pat. No. 5,889,475, issued to Klosinski, describes alert transmissions across AM and FM frequencies to warn vehicles through existing radio devices.
In summary, lights and sirens currently serve the purpose of general notification to surrounding drivers of a nearby emergency vehicle, but emergency vehicle-based lights and sirens are limited in the quality of information provided to other drivers. More specific notification technologies (as discussed above) generally require installation of specialized equipment directly within emergency and non-emergency vehicles to enable an alert service. It would be desirable to provide suitable notification to drivers regarding the direction of approach of an emergency vehicle, without requiring installation of specific equipment within the non-emergency vehicles.